Zip fasteners with two sliders are often used in various applications where a degree of security is desirable. Locking or securing the zip fastener can be achieved by locking each of the sliders to a stationary fixture, or else by locking the two sliders together. Each zip slider may be connected to a proximal end of a pull tab, with an aperture being formed in the opposing distal end of the pull tab. This arrangement allows for a securing device, such as the shackle of a padlock or a cable tie, to be fixed through both of the apertures in the distal ends of the pull tabs, to thereby lock the two sliders together and secure the closure. Advantageously, two sliders connected in this manner can still readily be moved together along the stringers as desired, by grasping one or both of the connected pull tabs in the conventional way. In addition, on a luggage item for instance, it is known to provide a key or combination locking system which has a sliding pin that can be extended through the aperture in the distal end of a pull tab, for securing the slider to the luggage item in place.
One of the drawbacks of locking the distal ends of the pull tabs in place, or to one another, is that doing so does not ordinarily prevent the sliders being separated sufficiently to create a small opening. In some cases this poses a security risk, if a thief can insert his fingers into the opening and work the stringers through the stationary sliders to enlarge the opening. This problem has been addressed in some prior art tamper resistant zip fasteners by providing coupling parts on the sliders for locking the sliders themselves directly to one another, however, such solutions require the manufacture of special-purpose sliders with interlocking features, which makes this a more costly option.
The publications US20090106951 and US20050257351 both describe a type of zip fastener in which the pull tabs on respective sliders interlock with one another, and in which the proximal ends of the pull tabs are connected to the sliders by couplings permitting the pull tabs to rotate about an axis transverse to the longitudinal axis of the stringers. Relative rotation between the pull tabs about the transverse axis is needed to place them in their interlocked positions. A disadvantage of both of these zip fasteners is that although they provide some basic degree of security for the closure, neither includes any provision for a higher degree of security, as is achieved, for instance, by connecting the pull tabs with a padlock.
With the device of US20090106951 in its interlocked position the pull tab on each slider overlies the adjacent slider, such that the pull tabs are aligned longitudinally, face in opposite directions, and are generally coplanar and close to the slider. When interlocked, the pull tabs cannot be conveniently grasped, so this prevents the two sliders being readily be moved together along the stringers. In the device of US20050257351 one pull tab has a male and the other a female coupler, the axes of which are aligned longitudinally in the interlocked position. A drawback of this alignment is that, intuitively, a thief would tend to pull the pull tabs apart in the longitudinal direction to separate the sliders and open the zip fastener, so this arrangement would not defeat even the most quick or casual attentions of a thief.
It is an object of the present invention to overcome or substantially ameliorate the above disadvantages or, more generally, to provide an improved zip fastener and luggage.